Huge Disclaimer to this: Think about it really hard if you can just use her as a fuck buddy and not have an emotional connection because if you can't do that then you will end up getting hurt much worse.
Turning an ex-girlfriend into a Fuck-buddy
First of all you need to get over her and that is truly the hardest thing to do. Before you plan to do this or try to do this I would recommend at least a month of no talking between you after the break up. During this month go out with other girls, improve your life, basically try to became the best PUA you can become this is essential. After this time period I would call her up and see if she is available to do anything get coffee, grab lunch, nothing that would insinuate that you are trying to get back together with her because you aren't...and if you are then you have learned nothing from this entire community. Now if she says she can't do anything fuck it she's not worth it move on to the next girl like you should have been doing already. Now during this meet up, first of all it much be very short and you must walk into it with such undeniable confidence that you haven't missed her for a day and the break up actually benefited you by making you into a better person. (Of course you never say this directly)
NEVER EVER talk about the relationship EVER or how it was or how you missed her during the time you didn't talk or how you thought about her NOOOO. Honestly the only way you can actually do this is if you sincerely believe that by breaking up it changed your life and made it so much better and you learned so many things and now have so much more confidence. During this "date" ALWAYS smile ALWAYS look at the eyes and ALWAYS have complete control of the conversation. If she ever brings up the relationship do not give your opinion about it do not argue with her just change the subject as quickly as possible. Water under the bridge. Basically during the date run your usual game that is assuming you have some. Tell stories that have huge DHV spikes, etc. Never talk about other girls unless asked because if you voluntarily give that information she will know you are trying to make her jealous and NEVER ask her about other girls you DO NOT care what she has been doing it DOES NOT affect you at all. (If it does affect you do not try to do this). End the conversation early at most an hour because you have other plans that you need to get to. Make sure you leave her wanting more at the end of the conversation.
The key goal in my mind is to become friends with her again and then make her realize that it would not be awkward at all if you were involved physically as long as there was no emotional attachment.
Remember this is NOT for the faint of heart and NOT everyone can emotionally take doing this.
Anyone want to add to this?